Noun

(wikipedia expertise) (-)

Great skill or knowledge in a particular field or hobby

The scientist has expertise in the field of nuclear fusion.

* 2014 , Michael White, " Roll up, roll up! The Amazing Salmond will show a Scotland you won't believe", The Guardian , 8 September 2014:

He spoke of Scotland's hydroelectric projects in Africa, local expertise shared with the world's poor.

advice, or opinion, of an expert

Noun

(en noun)

(informal) A geek with expertise in technology, especially computers.

* 1992 , Carl Malamud, Exploring the Internet: a technical travelogue (page 111)

Being able to use electronic mail, for example, should be a prerequisite to getting a piece published and certainly won't cause a writer to transform into a technogeek .

*{{quote-news, year=2007, date=September 6, author=Penelope Green, title=Romancing the Flat Pack: Ikea, Repurposed, work=New York Times citation

, passage=Do-it-yourselfers and technogeeks , tinkerers, artists, crafters and product and furniture designers, the hackers are united only by their perspective, which looks upon an Ikea Billy bookcase or Lack table and sees not a finished object but raw material: a clean palette yearning to be embellished or repurposed. }}